This paper addresses the rotordynamic instability of an overhung rotor caused by a hydrodynamic moment due to whirling motion through the structural coupling between whirl and precession modes. First, the possibility of instability is discussed based on a vibration model in which the hydrodynamic forces and moments are assumed to be smaller than structural forces with the structural coupling being represented by a structural influence factor. Then, the fundamental characteristics of rotordynamic moment on the backshroud of a Francis turbine runner under whirling motion were studied using model tests and numerical calculations. The runner is modeled by a disk positioned close to a casing with a small radial clearance at the outer periphery. The moment is caused by an inward leakage flow that is produced by an external pump in the model test. The experiments were designed to measure the rotordynamic fluid force moments under various leakage flow rates with various preswirl velocities and various axial clearances between the backshroud and casing. The computation was carried out based on a bulk flow model. It was found that the fluid force moment is generally destabilizing, except for a small region of positive whirling speed ratios.
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e-mail: horiguti@me.es.osaka-u.ac.jp
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July 2010
Research Papers
Rotordynamic Moment on the Backshroud of a Francis Turbine Runner Under Whirling Motion
Bingwei Song,
Bingwei Song
School of Hydraulic Engineering, Faculty of Infrastructure Engineering,
Dalian University of Technology
, Dalian 116024, China; Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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Hironori Horiguchi,
Hironori Horiguchi
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science,
e-mail: horiguti@me.es.osaka-u.ac.jp
Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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Zhenyue Ma,
Zhenyue Ma
School of Hydraulic Engineering, Faculty of Infrastructure Engineering,
Dalian University of Technology
, Dalian 116024, China
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Yoshinobu Tsujimoto
Yoshinobu Tsujimoto
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science,
Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
Search for other works by this author on:
Bingwei Song
School of Hydraulic Engineering, Faculty of Infrastructure Engineering,
Dalian University of Technology
, Dalian 116024, China; Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
Hironori Horiguchi
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science,
Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japane-mail: horiguti@me.es.osaka-u.ac.jp
Zhenyue Ma
School of Hydraulic Engineering, Faculty of Infrastructure Engineering,
Dalian University of Technology
, Dalian 116024, China
Yoshinobu Tsujimoto
Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science,
Osaka University
, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, JapanJ. Fluids Eng. Jul 2010, 132(7): 071102 (9 pages)
Published Online: July 8, 2010
Article history
Received:
May 11, 2009
Revised:
May 12, 2010
Online:
July 8, 2010
Published:
July 8, 2010
Citation
Song, B., Horiguchi, H., Ma, Z., and Tsujimoto, Y. (July 8, 2010). "Rotordynamic Moment on the Backshroud of a Francis Turbine Runner Under Whirling Motion." ASME. J. Fluids Eng. July 2010; 132(7): 071102. https://doi.org/10.1115/1.4001802
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